3-Way Solenoid Valves (COMMON) A step up from 2-Way valves. These have an air inlet, an air outlet and an exhaust port. There are 3 main advantages to a 3-Way valve versus a 2-Way valve: 1. They allow a much greater amount of air to flow through the valve and into your prop. Great for props that need a lot of lift or a quick lift. 2. They can be used with Single-Acting Cylinders with or without an air hole because the air can escape back through the solenoid and out the exhaust port (if open). 3. They allow you to control the exhaust coming out of the solenoid if you want to slow down the action on the tail end of your prop's motion. Has two 3/8" air ports and one 3/8" breather port. Comes with: 3/8" 3-Way Solenoid (2) 3/8" Male Straight fittings with 3/8" push-in female (1) Brass Breather Vent Available with 12-Volt, 24-Volt, or 110-Volt Flying Lead